This research proposal seeks to understand the nature of the interaction between alpha-lactalbumin and galactosyltransferase, and how the specificity of galactosyltransferase is modified by alpha-lactalbumin. The method of investigation includes chemical modification by photoaffinity labels. Any conformational changes associated with the interaction between the two proteins will be studied by fluorescence, spin labeling and circular dichroism techniques. It is also proposed to study the interaction of the catalytic and regulatory subunits of cAMP dependent protein kinase from bovine heart by using similar approaches.